This book is envisioned to be an appropriate launchpad into the world of nanoscale materials. It caters to the needs of undergraduate and postgraduate engineering students treading the challenging realm of researching nanoscale semiconducting devices. The scheme of things involved in the book is highly recommended for all beginners into this field. A sufficient background on nanotechnology, microprocessor, programming aspects and material characterization techniques has been duly addressed in this book via a programmable Chemical Bath Deposition(CBD) technique. The introduction sifts through a comprehensive literature on nanocrystalline semiconductors , thin films, CBD, diodes and optical filters. A general discussion on the fabrication techniques for the diodes and optical filters is included in order to appreciate the effectiveness of the proposed technique. The nanometric semiconducting devices such as short diode and short wavelength filter, fabricated using the technique handled in this book are examined with simple and reliable investigation methods to support its applications in optoelectronics.